Stress-Induced Changes in Accumulation of Sorbitol and in Activities of
Concomitant Enzymes in Digestive Gland of Freshwater Snail

I. L. Tsvetkov* and A. S. Konichev

Received February 16, 2009; Revision received March 25, 2009
Sorbitol content was determined in the digestive gland of freshwater
snail (Viviparus viviparus L.) in different seasons and in a
short-term experiment on the water temperature decrease and on
intoxication with cadmium chloride. In the model experiments, changes
in activities of enzymes involved in sorbitol metabolism (acid
phosphatases, sorbitol dehydrogenase, and aldose reductase) were also
studied. Sorbitol was accumulated by the snail in response to the
temperature decrease (as a cryoprotectant) and under conditions of
acute intoxication (as a probable metabolic regulator or a nonspecific
protective factor). However, the mechanisms of this accumulation are
different: on cold adaptation sorbitol is produced as a result of
reduction of glucose under the influence of aldose reductase, and on
intoxication sorbitol is mainly produced from fructose under the
influence of sorbitol dehydrogenase. Pathways of the sorbitol
accumulation and its re-involvement into metabolism are not always the
same, and this might be a mechanism for regulation of carbohydrate
metabolism (at the initial stage of glycolysis) on adaptation to
unfavorable factors of the environment.
KEY WORDS: mollusks, cold adaptation, intoxication,
cryoprotectants, sorbitol metabolism